


Of Fish, Detectives and Something In-between

by Fiachra



Series: Strandloper [1]
Category: Sherlock (TV)
Genre: Alternate Universe - Merpeople, Crack Treated Seriously, Gen, Magical Realism, Merlock, Merman Mycroft, Merman Sherlock, Merpeople, Platonic Sherlock Holmes/John Watson, Sea Monsters, Sherlock Holmes & John Watson Friendship, of sorts, partly inspired by the Ingo series by Helen Dunmore, platonic johnlock - Freeform, you'll have to wait and see
Language: English
Status: Completed
Published: 2016-03-17
Updated: 2016-03-17
Packaged: 2018-05-27 04:46:36
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,669
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6270157
Author URL: https://archiveofourown.org/users/Fiachra/pseuds/Fiachra
Summary: <blockquote class="userstuff">
              <p>"All in all, the day John's perception of the world turned upside down began in an ordinary fashion."</p><p>Sherlock is...different. Unique. Almost a legend in his own right. But John could never have imagined just how appropriate that last description would turn out to be...</p>
            </blockquote>





	Of Fish, Detectives and Something In-between

**Author's Note:**

> I don't know who came up with this AU. It's nuts. But it's imaginative and I love it. So here is the first Sherlock story I started writing (after many rewrites) split into oneshot format for your enjoyment (hopefully).
> 
> One of my motivations for writing this was the lack of stories in this AU that didn't revolve around smut or slash. So here is a platonic merlock story, no slash, no smut and no kinks. And with the minimum of crackiness. (However if you really want to read this with your shipper goggles on, go ahead.)

_“I must be a mermaid, Rango. I have no fear of depths and a great fear of shallow living.”_

-Anaïs Nin

David Miller sighed with relief as he exited the office building in Canary Wharf. It had been a long and stressful day, filled with two meetings, several conference calls and angry words with his incompetent intern. He was delighted at finally being able to return home. It was a bitterly cold evening and the icy breeze caused murky clouds to whisk across the rapidly darkening sky. Gripping his briefcase, he turned his collar up against the wind and set off at a brisk pace towards the Tube station. A splash caused him to pause and turn his attention to the docks. Tiny wind-whipped crests chased each other across the surface, illuminated by the orange street lamps, and lapped gently against the concrete bank. The sound he had heard had been louder than that. Intrigued, he moved nearer, peering into the gathering gloom, for the street lights didn’t reveal all of the dark water. Suddenly what appeared to be the fin of an enormous fish broke the surface along with the faintest glimmer of scales before vanishing as quickly as it had appeared. David blinked rapidly and rubbed his eyes. He waited for a few minutes, shivering when the wind picked up but it was gone, whatever it was, and so he turned and hurried towards his original destination, making a mental note to avoid working so late in the future. From the shadows between the watery orange reflections of the lamps a pair of pale blue eyes watched him disappear from view, before sinking silently below the water’s surface.

oOo

“John, get up we have a case!”

“Wha-“

But Sherlock had bounced out of sight before John could tell him off for coming into his room without permission. John sighed, got dressed, tried to take in Sherlock’s excited summary of what had happened on the taxi ride to the scene and tried not to dwell too much on the fact that everyone they passed seemed to be eating food of some sort while he definitely was not. All in all, the day John’s perception of the world turned upside down began in an ordinary fashion.

As the cab pulled up to a nice row of houses in Kensington, John had woken up sufficiently to pluck up the courage to ask Sherlock to repeat himself. Sherlock sighed irritably but complied as they strode past other Yard officials and up the stairs to the first floor.

“Locked room mystery. No apparent signs of murder or suicide, according to the victim’s wife, but then again, what does she know?” They were standing at the flat’s door at this stage, and a hassled looking Lestrade let them in.

The first impression John got was one of wealth. The flat was spacious and decked out in modern, expensive looking furniture. It was a bit too bland for John’s taste, nearly everything was in shades of white or cream, as if it had being designed specifically to be featured in a magazine of modern homes. The only splash of colour came from a large fish tank that served as a divider between the kitchen, which was heaving with every appliance under the sun, and the living room, which they were standing in. The wife, who like the rest of the flat was dressed expensively from head to toe and had dark tracks of eyeliner running down her face, was sobbing noisily to Donovan, who did not look impressed at all.

“He used to listen to loud music whenever I was out! That’s why he always locked the door, because he could never hear anyone coming!” she wailed while Donovan tried not to wince from the shrill voice she was been forced to endure at such close range.

“Unfortunate for him, what do you think? Sherlock?” John frowned. Sherlock was staring at the tank, a faraway look on his face. “Sherlock? You okay?”

“Yeah, fine.” He said distractedly before drifting over to the aquarium. John followed, amazed when Sherlock ignored the body in front of the tank and peered into it. Lestrade gave John a puzzled look, who shrugged in response. It was impressive, even from someone who knew nothing about fishkeeping. About four feet long, it was stocked with a shoal of large yellow fish, which seemed to be regarding Sherlock curiously, corals and some other fish in myriad colours.

John shook his head and knelt beside the prone corpse and began his quick examination. He looked up as Greg joined him. “Well, there’s nasty puncture wound and swelling on his hand, it doesn’t look suspicious but…” He shook his head. “Sherlock, do you not want to have a look? Sherlock!” Sherlock whirled around, blinked and looked down at John. 

“What?”

John looked at him incredulously. “Body. Don’t you want to examine it?”

Sherlock ignored him and turned to the dead man’s wife, John noticed that the yellow fish (what _were_ they called?) seemed to be watching Sherlock’s movements intently. “How long has he had the tank?”

“I’m sorry?” She asked in confusion, wide eyes staring at him from her mascara-smudged face. Sherlock sighed theatrically. “The fish tank! How long had your husband had it?”

.“About a month, he got the suppliers to get everything ready for him, so he could start straight away-“ Sherlock motioned her to be quiet and looked back at the body.

“Well? What happened?”

“You saw the swelling on his hand, didn’t you?”

“Yes, but-“

“As ever, you see but you don’t observe John!”

Sherlock rolled his eyes at the blank looks on everyone's faces and launched into his usual rapid-fire deductions. “It’s a new tank, saltwater, usually the realm of experienced hobbyists, which he clearly wasn’t if his stocking levels are anything to go by. If any of you had taken the time to look, you would have seen that this rock had fallen, quite recently, the pale underside is exposed. It’s blocking this coral’s light,” he pointed it out “So he tried to move it, only to get stung by something underneath the rock. Something, that if you’re allergic to it, can cause heart failure and death.”

“Which is?” Greg prompted.

Sherlock, only too happy to point it out, pulled off his coat, rolled up his shirt sleeve and plunged his hand into the tank, much to everyone’s protests. Gently swatting the yellow fish aside, who seemed delighted that Sherlock was sharing their space, he carefully lifted a piece of rock and withdraw his arm quickly. John and the others crowded around him. As the sand settled, they saw a large, grumpy-looking red and white striped fish flare its enormous fins aggressively at them.

" _Pterois volitans_ , the Volitans lionfish.” Sherlock said. “Hardy, not usually deadly, but still not the best fish for a novice. I suggest you class his manner of death as accidental once the autopsy report shows I’m right and arrange for his livestock to be rehomed, preferably to more responsible owners. Keep the tangs together though, they seem to like each other’s company.” He replaced the rock, scowling at the lionfish as it spread its fins towards him and rubbed his arm dry with an offered towel.

“Well, um, thanks. You can go if you want.” Greg said to John, who nodded.

“Ready Sherlock?”

Sherlock looked away from the tank and blinked at him. “Sorry?”

“You solved the case, we can go?” said John slowly, as if Sherlock had forgotten what usually happened on cases.

“Yes, of course.” Sherlock said, seemingly back to normal. “Give me the details of whoever you call to deal with the fish.” He said to Greg as he headed to the door, who nodded in confusion. John followed, after giving the yellow fish an odd look, they looked like they were sadly watching Sherlock leave, like spurned puppies.

“So I guess you could say that case was a bit “fishy”.” John heard Anderson say as he shut the door behind him.

“Shut up Anderson!” and groans were the resounding answer.

oOo

“So how did you know all that?” John asked in the cab home.

“Know all what?” Sherlock said coyly.

“About the fish and fishkeeping. I know it was venomous and that’s probably relevant information to you, but you usually never show much interest in animals.”

“I like marine animals.” Answered Sherlock nonchalantly, gazing out of the window.

“Really? I never knew.”

“There’s a lot you don’t know about me John.” Was the soft reply.

John was about to make a sarcastic comment about that not being the case if Sherlock would only talk about himself more, but stopped when he saw Sherlock’s expression. He was looking out the window with an odd look on his face, similar to what he looked like when he saw the fish. He looked, sad, as if he was longing for something.

John turned to look out his own window, thinking. Sherlock was acting odd (well, odd _er_ ), to be more captivated by ornamental fish than a corpse? And now to stare out of the window like some wistful lover in an old film? What was with him today? John was baffled.

Sherlock was quiet when they walked up the stairs to the flat. He hadn’t spoken a word since the beginning of the cab ride. The solemn silence was starting to worry John, and just as he opened his mouth to ask what on Earth was the matter with him when he shut the door behind them, Sherlock said, “I’m taking a bath.”

“Um, okay?” John said as Sherlock vanished down the hall. “Are you alright?” Sherlock never usually announced when he wanted to use the bathroom for something, which had led to some sights over the years that John could have gone his entire life without seeing.

“I’m fine.” Came Sherlock’s muffled reply before the door banged shut.

oOo

When John returned about an hour later from a walk and the shop, 221B was oddly quiet. Too quiet. He frowned as he placed the shopping bags on the table. Sherlock’s coat was still hanging up, and his phone was next to his microscope, so he hadn’t gone out. His bedroom door was open and he wasn’t in there either. So if he wasn’t in his room, or in the rest of the flat and he hadn’t gone out…. John looked at the bathroom door, which was still shut. Really? After this length of time? He stepped forward, and hesitated. This was Sherlock, he was probably fine. But then again… He tapped lightly on the door. “Sherlock? Sherlock? Are you in there?”

No answer.

Feeling a bit apprehensive now, John tried the handle. Locked, of course. Moving into Sherlock’s room, he knocked again. “Sherlock, I’m coming in.” At the lack of response, he pushed open the door and entered the bathroom.

And then proceeded to let out a high-pitched shriek of, “Jesus Christ!”

Sherlock awoke and jumped, sloshing water over the side of the bath. “John!” he yelped in surprise, “I can explain…” At that moment, Mrs. Hudson’s voice reached them from downstairs, “Are you two alright?”

“We’re fine.” John managed to call back, shutting the door behind him and sliding down it to sit on the tiled floor.

“Are you? You don’t look it.” Sherlock said in concern.

“I’m…” John looked at Sherlock’s legs, only they weren’t, they were scaly, and… “Actually, I’m not sure if I am…”

“Don’t pass out. Just, shut your eyes and breathe.”

John did, and concentrated on breathing in and out. He could hear Sherlock shift in the bath, but otherwise remain quiet. After a minute, John opened his eyes, gingerly stood up, moved closer to Sherlock and knelt next to the bath, Sherlock watching him warily. “Is that…are you…” John swallowed “are you a…a mermaid?”

Sherlock sighed. “I’m male, John, in case you hadn’t noticed.” But then he softened slightly. “But yes, I suppose “merman” would be an appropriate term.”

“How?” John stared unabashedly at the gleaming, fish-like tail that had replaced his friend’s legs. “This isn’t a trick is it? You didn’t spike my tea did you?” He pinched his arm, and winced. Not a dream either then.

“This isn’t a trick, nor did I spike your tea.” Sherlock huffed in indignation at the thought. “As to how…” he shrugged. “There was an old story on my mother’s side of the family that one of her ancestors was a mermaid, and ever since then they had a particular affinity with the sea. Well, it was just a story until Mycroft and I were born.” He flicked his tail, drawing John’s attention to it again.

It began at his hips, pale skin transitioning smoothly and seamlessly to scales, and added to Sherlock’s height by about two feet at the most and tapered to an elegantly curved caudal fin. Noticing John’s interest, Sherlock turned on his side, exposing a spiky dorsal fin that ran from the centre of his shoulder blades to the small of his back. The colour of his tail was not unlike that of a mackerel, except without the black stripes. Darkest on top, it gradually paled to cream on his underside. More scales extended from his tail and continued up his spine, clustering around the base of his dorsal fin, terminating at the base of his skull. He rolled on to his back again, causing a silver shimmer to run along his tail. “You can touch, if that helps.”

“Really?”

Sherlock nodded, light glinting off small, lightly coloured blue-green scales on his cheekbones. Similar ones were scattered along his forearms, and when he waved a hand in his tail’s direction, translucent webbing connected his fingers. John cautiously rolled up his sleeve and laid his hand on Sherlock’s tail. To his pleasant surprise, it wasn’t slimly like some fish he remembered catching as a kid. Instead it was smooth and seemed to be packed with muscle. He ran his hand down towards the fin, eyes wide in wonder.

“That’s…amazing.”

Sherlock’s mouth quirked up in a smile. “Convinced it’s real now?” John nodded.

“Good, I thought you were going to faint for a moment when you came in.”

“To be fair, you turning out to be half fish isn’t exactly something I was expecting to see.”

“I’m not half fish,” Sherlock said indignantly, “I’m half Mer.”

“Mer?”

“Merfolk, merpeople, finfolk, dinny mara, aipalookvik, merrymaids, sea-morgans, merrows, take your pick. I think “Mer” sounds good though, dignified.”

“Of course you would,” John snorted, “I’m sorry about barging in on you, I thought something was wrong.”

“It’s fine.” Sherlock said. “Not the way I originally planned on telling you, but it was effective.” John blinked. “You were going to tell me?”

“Of course. “ _“Potential flatmates should know the worst about each other”_ ,” he recited, “Friends even more so.” John flushed at the unexpected sentiment. “Why are you in here anyway?”

“Becoming Mer is like an itch I need to scratch every now and then, and it’s nicer to do it in water. There’s too much of a risk during daylight to use the Thames, and I couldn’t wait until night. This is warmer anyway.” John nodded and sat back on his heels. “Okay, so this is really, really odd, but as long as you don’t try to drown me or anything, it doesn’t bother me.”

Sherlock narrowed his eyes, seeming to scan John in order to prove the validity of his statement. “Really? It doesn’t bother you at all?” John shrugged. “Why should it? You can grow a tail, it might take me a while to get my head around that, but it’s fine.”

Sherlock looked momentarily baffled, then smiled. “Thank you. Oh, and John?” he said as John started to leave, “Merpeople don’t usually drown soldiers, so you’ll be fine. If you were in the Navy on the other hand…” He grinned mischievously.

John’s expression, from Sherlock's point of view, was priceless.


End file.
